In this thesis, an integrated wind erosion assessment and prediction system has been developed. This system couples a physically based dust emission scheme, a high resolution limited area weather prediction model, a dust transport model, and a high resolution GIS (Geographic Information System) database. A simple expression for particle threshold velocity has been derived by considering the force balance of a single particle resting on the surface. Theoretical analyses have been performed to confirm that the main mechanism for dust uplifting is sand saltation bombardment rather than direct aerodynamic entrainment. A new model for dust emission by saltation bombardment is proposed and validated against experimental data. Preliminary sensitivity tests for the new dust emission model have been carried out by examining the dependence of dust emission rate on a range of parameters. The transport of airborne dust is modelled by using the particle mean concentration equation. The time-dependent advection terms are discretized and solved numerically by a multi-dimensional wave-propagation slope-limiter scheme. Some computational features of the integrated model are discussed in terms of its coupling, module decomposition, data handling and efficiency. A systematic sub-grid treatment is designed to extract soil surface parameters from the GIS database for large scale modelling. The integrated system is applied to investigate the February 1996 dust storms over the Australia continent. The simulated wind erosion pattern and intensity are in good agreement with available meteorological records and satellite images. It reveals that the system can be used to identify areas and periods under wind erosion threat as well as the responsible environmental factors.

Följande studie har utförts på begäran av energiföretaget Norrenergi AB, där det finns en önskan att tillförlitlighetssäkra den nuvarande driften av stofttransportsystemet tillhörande två av värmeverkets hetvattenpannor. Studien har undersökt huruvida det finns möjlighet att framförallt minska underhållskostnaderna. Studien har framförallt inriktats mot två stofttransportfläktar som vardera tillhör ett stofttransportsystem, eftersom mycket underhållsarbete lagts på de fläktarna. En jämförelse med andra liknande verk har även utförts då det visats att Norrenergi AB:s lösning av stofttransporten är ytterst ovanlig. Vidare har en analys av fläktarna utförts, vilken visade att de är underdimensionerade för systemet. Det har konstaterats utifrån genomförda SPM-, temperatur- och bullermätningar. Olika typer av lösningar på problemet har undersökts och då på en förändring av hela systemet, alternativt enbart av fläktarna eller lagren till stofttransportfläktarna. Rapporten har utmynnat i flera förslag vilka innefattar en ny systemutformning, installation av nya fläktar samt en uppgradering av det nuvarande systemet, där installation av nya fläktar rekommenderas. / This study has been carried out at the request by the energy company Norrenergi AB. It consists of an analysis on how they can reduce the maintenance regarding two dust transporting fans installed in the flue gas cleaning compartment of their thermal power plant. The study also compares what solutions other plants have regarding the dust-transport. The solution installed at Norrenergi AB was found to be rather unusual. Measurements and calculations have been performed to investigate further what have caused the high maintenance on the fans. The study looks into what upgrades are available to the entire dust transporting system. The result of the study turned into different suggestions, which includes a new configuration of the dust transporting system, and installation of new fans and also an upgrade of the existing dust transporting system. Among the suggestions the final recommendation is the alternative of installing new fans.

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